Fluid motors of the percussive type



Sept. 24, 1957 F. F. CHELLIS 2,807,021

FLUID MOTORS OF THE PERCUSSIVE TYPE 7 Filed Feb. 10, 1955' 4 3Sheets-Sheet, 1

[nus-afar Fred E'Chel/is Sept. 24, 195

Filed Feb. 10, 1955 7 F. F. C ELLIS 2,807,021

FLUID MOTORS OF THE PERCUSSIVE TYPE 5 Sheets-Sheet 3 fm/cnlor UnitedStates Patent FLUID MOTORS OFTHE PERCUSSIVE TYPE Fred F. Chellis,Manchester, Mass, assignor to United Shoe Machinery Corporation,Flemington, N. J., a corporation of New Jersey Application February 10,1955, Serial No. 487,317

22 Claims. (Cl. 1101) The present invention relates to fluid motors ofthe vented to atmosphere allowing the valve itself to be opened by thepressure in the high pressure chamber nicates with the low pressurechamber to provide a large percussive type and more particularly topneumatic motors of the type used for driving fasteners by impact.However, it is to be understood that various features of the presentinvention are not thus limited in their utility.

Percussive type fluid motors are basically very simple and comprise acylinder housing a piston which is moved therein by fluid pressure. Theconstruction of such motors becomes more complicated when they aredesigned for maximum efficiency, obtaining maximum utilization of thefluid pressure and, in the case of pneumatic motors, minimizing fluidconsumption. In the field of pneumatic, portable or hand-held fastenerinserting devices or guns, efficient use of the operating fluid is ofparticular importance. It is of course desirable that the air motorsused in such guns be of minimum weight to minimize operator fatigue andthat they require a minimum of effort to operate. Preferably, such gunsshould be designed to drive nails and other types of fasteners to therequired depth by a single blow. Thus the air motor used to drive thefastener should have percussive action and be readily adapted to singlecycle operation. Furthermore, since various size nails may be driven byone gun, a serious problem of shock absorption may arise if a gun isused to drive nails which are substantially smaller than the maximumsize for which the gun was designed.

It is therefore a principal object of the present invention to providean improved fluid motor of the percussive type.

A further object of the invention is to provide an improved pneumaticmotor having means for minimizing the amount of air needed for itsoperation.

Yet another object of the present invention is to provide an improvedfastener inserting device of light weight construction which is easy toactuate and which may be operated with a minimum of fluid consumption.

My invention is herein disclosed in a novel fastener inserting gunembodiment.

In accordance with the various features of the present invention thereis provided a fluid motor of the reciproeating type wherein pressurizedfluid is introduced into chambers on either side of a piston with thepressure in one chamber being lower than the pressure in the otherchamber and the fluid in the higher pressure chamber is vented to allowthe piston to be driven by the lower pressure fluid. Preferably a singleair supply line is provided and a pressure regulating valve mounted atthe entrance 7 to the low pressure chamber controls the pressuretherein. Thus the fluid in the low pressure chamber need not be ventedas the piston is returned in each cycle by repressurizing the highpressure chamber. Provision is made for adjusting the pressureregulating valve so that the energy imparted to the piston may bematched to the particular requirements thereof.

An internal control valve seals off one end of the high pressure chamberfrom venting ports. Fluidpressure normally maintains this valve in itssealing positron and, when the piston is to be driven by the lowpressure fluid, is

storage capacity of. pressurized fluid while at the same time protectingthe air motor from injury.

A pilot valve may be operatively connected to the nose piece of theinserting gun for controlling the pressurized fluid which maintains thecontrol valve inits sealing position.

Yieldably mounted locking means are provided for preventing fastenerswhich are automatically delivered to the inserting gun from beinginadvertently discharged therefrom.

The above and other features of the invention including various noveldetails of construction and combination of parts will now be moreparticularly described with reference to the accompanying drawings. andpointed out in the claims.

In the drawings,

Fig. 1 is a view showing the general outline of the fastener insertinggun of the present invention;

Fig. 2 is a schematic view of the inserting gun associated withautomatic means for delivering fasteners thereto;

Fig. 3 is a crosssection of the gun shown in Fig. 1 on an enlarged scalewith the driver in its inactive position;

Fig. 4 is a view similar to Fig. 3 with certain portions omitted andwith the driver in its released position;

Fig. 4a is a view of the nose piece of the gun showing the relation ofcertain parts immediately after the gun has been removed from aworkpiece;

Fig. 5 is a section taken on the line VV inFig. 3;

Fig. 6 is a section taken on the line VIVI in Fig. 5;

Fig. 7 is a section taken on the line VII-VII in Fig. 3;

Fig. 8 is a section taken on the line VIIL-VIII in Fig. 3; and

Fig. 9 is a section taken on the line IX-IX in Fig. 3.

For simplicity certain specific terms will. be used in the followingdescription which are not intended in any way to limit the breadth ofthe invention. For example, certain aspects of the invention areapplicable to fluid motors generally although an air motor is describedfor operating the inserting gun. While the inserting gun itself isadaptable to drive all types of fasteners which are driven by an impactblow reference is made only to nails. Other terms are used in thefollowing description which are likewise not intended to place anylimitation on the breadth of the invention as will be obvious from areading of the claims.

Referring now to Fig. 1 an inserting gun 20 is shown in outline form.This type of gun is adapted for portable operation to insert nails. Ahandle 22 enables an operator readily to position the gun 20 and drivenails into workpieces by pressing its nose piece 24 against a workpiece.This'type of gun is preferably used in combination with means forautomatically delivering one nail at a time to the inserting gun inresponse to'the operation of the gun. Nail delivering means areindicated schematically in Fig. 2 and will be described in detail below.The inserting gun 20 is provided with an air supply line 26, a naildelivery tube 28 and a signal line 30. The lines 26 and 30 and the tube28 are formed of metal tubing for the short distance along the length ofthe gun 20 with one end of each being mounted in a plate 32. Beyond thegun 20 the lines 26 and 30 and the tube 28 are formed of flexibletubing, preferably of some synthetic rubber-like material, whichcontinue to a remote W. Air may then flow from the bore 80 (Figs. 2

operated simply by pressing the nose piece 24 of the gun againstworkpieces which are to be fastened.

The inserting gun 20 is of extremely light and rugged construction andprovides a maximum usage of the energy of the compressed air all ofwhich will become more apparent from a detailed study of theconstruction shown in Fig. 3 and various other detail views. The gun 20'is provided with an outer casing 38 to which the handle 22 is attachedby a metal band 40 (Fig. 1). Within the casing 38 is a concentriccylinder 42 in which a driver piston is slidable. A driver 46 is securedto the piston 44 by a nut 48 and extends downwardly within the cylinder42 toward the nose piece 24. It will be appreciated that the driver 46is in effect a piston rod and therefore is equivalent to such should itbe desired to utilizethe air motor of the present invention in any otherapplication. The driver 46 and its associated piston 44 are shown intheir upper or inactive positions in Fig. '3 in readiness to drive anail positioned in the nose piece 24. This inactive position of theinserting gun 20 will first-be described.

A plug 50 is threaded into the lower end of the casing 38 and hasprojections 51 which space it apart from the lower end of the cylinder42 (Fig. 9). Another plug 53 is threaded into the upper end of thecasing 38, the plug 52 heing'provided with a recess 54 which providesmeans for positively locking the upper end of the cylinder 42 inconcentric relation with thecasing 38. An internal control valve 56seals off the lower end of the cylinder 42 and is provided with anopening 58 through which the driver 46 may pass. For convenience thespace within the cylinder 42 beneath the driver piston 44 will bereferred to as the lower chamber 60 of the inserting gun I 2. and thespace within the cylinder 42 above the driver piston 44 will be referredto as the upper chamber 62 of the inserting gun as seen in Fig. 3. Theannular space between the cylinder 42 and the outer casing 38 forms anaccumulator 64 for compressed air which is connected to the upperchamber 62 through a series of holes 66.

To locate the piston 44 in its upper or inactive position 'shown in Fig.3, compressed air is supplied to the lower chamber 60 in the followingmanner. The air supply line 26 has a collar 68 (Fig. secured to itslower which is fastened to the plug 50 by a specially formed screw 70.Air enters the gun 20 through the line 26, Ms around a reduced portion72 of the screw 70, through-radial passages 74, an axial passage 76, anda passageway 78 formed in the plug 50 to a two diameter bar-e80.

A ball check 82 is provided within the axial y 76 to prevent free flowof air from the insert to the line 26 for reasons which will hereinafterand 8) through an annular chamber 84 and holes 86 to the lower side ofthe control valve 56. Air then flows 11101181111116 opening 58 between apacking 88 and the drive to the lower chamber 60. The lower chamber 0 isthus maintained at the same pressure as the supply line .26. The.control valve 56 is maintained in its upper position sealing off thelower end of the cylinder 42 due to the fact that there is a greaterarea on its lower side subjected to line pressure than upon its uppersurface.

s upper chamber 62 of the gun 20 is maintained at a pressure below linepressure in the supply line 26 by means of the following mechanism.Referring to Fig. 8 it can be seen that the supply line 26 communicateswith a passageway 90 formed in the plate 32. The passageway 90 in turncommunicates with an annular chamber 92 surrounding an extension of theplug 52 and through radial passageways 94 formed therein to a pressureregulating valve 96. The valve 96 is normally main tained in its closedposition by a compression spring 98 which is seated in a recess formedin a screw cap 100. The screw cap 100 is threaded into the plug 52 andserves also to clamp the plate 32 in its proper position with respect tothe various elements of the inserting gun. The regulating valve 96controls flow of air through a passageway 102 to the upper chamber 62.The stem 194 of the valve 96 is fluted so that when the valve is raisedagainst the action of the spring 98 air passes through the passageway102 pressurizing the upper chamber 62 and the accumulator 64.

When the air supply line 26 is first connected to a source of compressedair, the lower chamber 60 of the inserting gun 20 first becomespressurized by flow of air through the various passageways, as explainedabove, moving the piston 44 in an upward direction thereby opening thepressure regulating valve 96 and admitting compressed air to the upperchamber 62 and the accumulator 64. As the pressure in the upper chamber62 increases, the force of the spring 98 will displace the piston 44downwardly closing the valve 96 before the pressure in the chamber 62reaches line pressure. It will be noted that the area of the uppersurface of the piston 44 is greater than that of the lower surface dueto the presence of the driver 46. This difference in area establishesthe minimum pressure differential which must exist between the chambers60, 62. With this arrangement the driver piston 44 and the driver 46 aremaintained in their inactive positions ready to drive a nail, as shownin Figs. 2 and 3. When compressed air is vented from the lower chamber60, in a manner to be described presently, the driver piston and thedriver are driven downwardly to the positions shown in Pig. 4 by thecompressed air in the upper chamber 62 and in the accumulator 64. Ascrew 195 threaded into the screw cap 108 is provided for adjusting theforce exerted by the pressure regulating valve spring 98. As was justdescribed the pressure in the upper chamber 62 and the accumulator 64 isdependent upon the spring load; thus this pressure may be varied byadjustment of the screw 105. A lock out 107 may be provided to maintainthe screw in proper adjustment. In this manner the energy imparted tothe driver piston 44 and the driver 46 may be matched to the type andsize of nail being driven thereby minimizing the shock imparted to thevarious elements of the gun.

When air is reintroduced into the lower chamber 60 after a nail isdriven, the driver piston 44 is returned upwardly, recompressing the airin the upper chamber 62 and in the accumulator 64. At this time thedriver piston 44 will not necessarily assume its uppermost positionbecause the pressure in the upper chamber 62 is only slightly below linepressure, this condition being illustrated in Fig. 3. During each cycleof operation of the driver piston 44, air may leak from the upperchamber 62 so that after several cycles of operation the pressuretherein will become reduced sufiiciently to permit the driver piston 44to be forced upwardly until the spring 98 is again overcome and airflows through the passageway 102 to return the pressure in the upperchamber 62 to the desired value. This arrangement effects a greateconomy of air in that only one chamber of the air motor need beexhausted in the operation of the gun while, at the same time it is notnecessary to provide auxiliary means for the return stroke of the driverpiston 44.

Venting of the lower chamber 60 to actuate the driver piston 44 and thedriver 46 is initiated by the relative displacement of the gun and apilot valve 106 one end of which rides in the smaller diameter portionof the bore 80 and the other end of which rides in the larger diameterportion of the bore 80 and in a concentric bore 81 of equal diameterformed in a nose piece bracket 108. The nose piece bracket 108 issecured to the plug 50 by screws 110. It will be noted that the lowerspool of the pilot valve 106 is of greater diameter than the upperspool. Therefore, air entering through the passageway 78 (Figs. 3 andnormally maintains thepil'ot valve 106 in its lowermost position,wherein the larger diameter spool is in the concentric bore 81, and inwhich air may pass to the lower chamber'60 in the manner describedabove.

As was pointed out above, the inserting gun 20 is operated by pressingthe nose piece 24 against a workpiece which effects relativedisplacement of the gun and the pilot valve 106. The nose piece and thepilot valve 106 are connected in the following manner: A hollow rod 112extends from the lower end of the pilot valve 106 to the lower end ofthe bracket 108 where a springfingered quill 114 is provided to positionnails in proper alinement with the driver 46. A quill retaining sleeve116 extends beyond the rod 112. The sleeve 116 may be secured to the rod112 by spring clips 119 as seen in Fig. 7 though a positive fastening isnot essential. Two screws 118 extend from either side of the sleeve 116and enter holes formed in the nose piece 24. It will be understood thatas .the gun is initially pressed toward the workpiece to drive a nailthe entire gun including the casing 38 and the nose piece 24 moves. Uponcontacting the workpiece, the motion of the nose piece 24, the rod 112and the pilot valve 106 ceases but the casing 38 and the remainingmechanism of the gun continue toward the workpiece a short distance.During this time the gun is actually moving relative to the stationarynose piece but for the sake of a simpler description of operation, aswill becomemore apparent hereinafter, the nose piece 24, the rod 112,pilot valve 106, and the mechanism fixed thereto will be described asmoving upwardly relative to the gun. Thus when the gun 20 is pressedagainst a workpiece, the nose piece 24 acting through the screws 118,the sleeve 116, and the rod 112 effects relative displacement of the gunand pilot valve 106. The compressed air acting on the lower side of thecontrol valve 56 vents to atmosphere through a hole 120 in the bracket108 as soon as the larger diameter spool of the pilot valve 106 ispositioned above the annular chamber 84 as is seen in Fig. 4, the airpassing through the holes 86, the annular chamber 84, around a reducedarea 121 formed on the rod 112 and out hole 120. When the lower side ofthe control valve 56 is thus vented to atmosphere, the pressure in thelower chamber 60 forces the control valve 56 downwardly at a rate whichis far greater than the corresponding control valve could be opened byhand operation and with greater consistency from one cycle of operationto another. Displacement of the control valve 56 vents the lower chamber60 to atmosphere through a series of radial passageways 122 (Fig. 9)which hitherto had been covered by the control valve. When the insertinggun 20 is removed from a workpiece, the pilot valve 106 again returns tothe position in Fig. 3 due to the greater air pressure force which is atall times effective upon its larger diameter spool.

The following provisions are made for the automatic delivery of nails tothe quill 114. The lower end of the delivery tube 28 is secured to thebracket 108 by a strap 124 and screws 126 (Fig. 1). An opening 128 isformed in the hollow rod 112 so that nails pass along the delivery tube28 through the opening 128 and into the quill 114. Since these nails aredelivered, preferably by a blast of compressed air, it is necessary thatmeans be provided to prevent them from being blown out of the nose piecewhen they are delivered. Therefore, a quill locking sleeve 130 isprovided to retain a nail within the quill. The quill locking sleeve 130rides within a nose piece mounting sleeve 132 which is secured to the brcket 108 by a pin 134 and a spring clip 136. The sleeves 130 and 132 areprovided with elongated slots 138 within the screws 118 ride and whichthereby limit the motion of the nose piece 24. It will be noted that thequill locking sleeve 130 has an internal ledge 130 which preventsoutward displacement of the spring fingers of the quill 114 when the gunis in its inactive or ready position shown in Fig. 3.

When the gun 20 is pressed against the workpiece, .there is' relativemovement between the nose piece 24 and the quill 114 with respect to thequill locking sleeve 130. The lowermost end of the quill 114 is taperedand it is thus possible for the spring fingers to be displaced outwardlywithin the locking sleeve as the driver 46 drives a nail therefrom as isillustrated in Fig. 4. When the inserting gun 20 is removed from aworkpiece, there is relative movement of the pilot valve and the partsconnecting it with the nose piece 24 with respect to the gun to admitair to the lower chamber 60 and initiate the return of the piston 44 andthe driver 46 to their inactive positions, as explained above. The quilllocking sleeve 130 must move at this time with the nose piece 24 becausethe driver 46 has not moved above the ends of the fingers of the quill 114 so that they are held in their outwardly displaced condition. It isthus necessary to provide a compression spring 140 which allows thequill locking sleeve 130 to move independently of the nose piecemounting sleeve 132 and then return it to the position seen in Fig. 3wherein the driver is shown elevated. The intermediate position of theseparts is shown in Fig. 4a. As soon as the driver is above the quill 114,the spring 140 will return the locking sleeve 130 to its normal positionshown in Fig. 3.

As was mentioned above, the present device is particularly adapted foruse with automatic means for delivering nails. It is therefore necessaryto provide signalling means for actuating the operation of thedelivering means. A passageway 142 (Figs. 3 and 6) extending from thebore 80 is provided for that purpose. The passageway 142 extends to anaxial passage 144 and radial passageways 146 formed in a screw 148. Thescrew 148 is threaded into the plug 50 and clamps a sleeve 150 securedto the lower end of the signal line 30 in a manner similar to theassemblage at the lower end of the air supply line 26. It will be notedthat when the pilot valve 106 is in its upper position (Fig. 4) thepassageway 142 is in direct communication with the air supply line 26through the passageway 78. Thus each time the pilot valve 106 is inposition to actuate the inserting gun 20 the signal line 30 becomespressurized at full line pressure.

There are many systems for automatic delivery of nails. One sucharrangement is shown in Fig. 2 in schematic form. The details of thissystem are fully described in application for United States LettersPatent Serial No. 427,022, filed May 3, 1954, in the name of Donald B.McIlvin. Particularly this system comprises a hopper 152 in which nailsare stored, a lift slide 154 for delivering nails to a raceway 156, anda separating segment 158 for bringing one nail at a time from the lowerend of the raceway to a point in alinement with .the delivery tube 28.An air motor 160 having a piston 161 is provided for actuating the liftslide 154 and the separating segment 158. A base 162 extends from themain control valve 36, which has a piston 163 slidable therein, andinterposed in the line 162 is a time delay valve 164 having a piston 164to provide a controlled blast of air for delivering each nail throughthe delivery tube 28 to the inserting gun 20. A pair of lines 165 and165' also extend from the control valve 36 to rightand left-hand sidesof the air motor 160 respectively. It will be noted that the signal line30 extends to the control valve 36. Thus when the signal line 30 ispressurized the piston 163 within the control valve is displaced from afirst or righthand to a second or left-hand position. This causes theiston 161 of the air motor 160 to be moved to the left by an increase inpressure in the line 165 and a decrease in pressure in the line 165,causing the lift slide 154 to deliver nails to the raceway 156 andmoving the separating segment in a counterclockwise direction so thataslot 166 formed therein is in alinement with the raceway. The pressurein the line 165 causes the piston 164 of the control valve 164 to: bedisplaced from the position shown in Fig. 2 to its right-hand position.However, it will be noted that the control valve 36 blocks passage ofpressurizedair through the line 162 at this time and vents the line 162to atmosphere. When the signal line is depressurized after the gun 20 isremoved from a workpiece, the piston 163 of the control valve 36 returnsto its first or right-hand position. The piston 161 of the air motor 16.moves to its right-hand position as seen in Fig. 2 thereby causing thelift slide 154 to move downwardly and the separating segment 158 to movein a clockwise direction whereby, the lowermost nail is carried by theslot 166 to a point in alinement with the delivery tube 28. Air thenflows through the line 162 to carry the separated nail through thedelivery tube 28 so that the nail N will become positioned within thequill 114 as is seen in Fig. 3. The time delay valve 164 is adjusted sothat only a short blast of air travels through the line 162.

In the present construction specific mention of the various seals andpackings which are used in the inserting gun 20 have been omitted.However, to avoid confusion the various seals will now be described. Allseals which are of circular cross section are annular rings of resilientmaterial commonly known as rings. 0 rings 168 provide static sealsbetween the nut 100, the plate 32 and the plug 52. An 0 ring 170provides a seating seal for the pressure regulating valve 96. An 0 ring172 provides a static seal between the plug 52 and the casing 38. An 0ring 174 provides a static seal between the casing 38 and the lower endof the cylinder 42. An 0 ring 176 provides a static seal between thecasing 38 and the plug 50. An 0 ring 178 is used as a packing for thedriver piston 44. An 0 ring 180 is used to provide sealing means for thecontrol valve 56 in sealing off the lower end of the cylinder 42. Astandard packing 182 is pro vided for the control valve 56. An 0 ring184 provides a seal between the bore 80 and the driver 46. 0 rings 1,188 are provided as packings for the pilot valve 106. O ringsl90, 192provide seals between the screws 70, 148 and the sleeves 68 and 150respectively. The packing 88 inside the control valve 56 has beenmentioned in the description above.

In the operation of the inserting gun 20 the parts are normally in theirinactive or ready positions shown in Figs. 2 and 3. The lower chamber 60is at full line pressure while the upper chamber 62 and the accumulator64 are at a pressure below line pressure. The control valve 56 ismaintained in its upper position by pressurized air from line 26 toreduced portion 72 of screw 70 (Fig. 5) then through radial passages 74,axial passages 76, '78 to bore 80. (Figs. 2 and 3), to annular chamber84 (Fig. 3),

holes 86, to the lower face of control valve 56 sealing off the lowerchamber 60 due to the fact that there is a greater area on its lowerface of the control valve 56 exposed to full line pressure. The pilotvalve 106 is maintained in its lower position due to the greaterdiameter of its lower spool. A nail N is positioned in the quill 114 inreadiness to be driven by the driver 46. The nail delivery parts are intheir respective positions shown in Fig. 2.

To drive the nail the operator grasps the handle 22 on the casing 38 andmoves the gun toward the workpiece until the nose piece 24 strikes theworkpiece which prohibits its further movement and that of the spoolvalve 106. A small amount of continued movement of the casing 38 towardthe workpiece causes the two diameter bore 80 to fully envelop the thenstationary spool valve 106 whereupon the pressurized air on the lowerside of the control valve 56 is vented to atmosphere through the holes86, the annular chamber 84 and the hole 120. The pressure in the lowerchamber 60 is vented to atmosphere through the then uncoveredpassageways 122 allowing the piston 44 and the driver 46 to be drivenwith a percussive force away from the inactive position and toward aforcedelivering positionby the air compressed within the upper chamber62 and in the accumulator 64 to drive the nail. The stroke of the piston44 hitting against the control valve 56 is absorbed by a rubber bumper194. This shock force, however, is minimized by maintaining the pressurein the upper chamber at a point Where the energy imparted to the driverpiston 44 is just sufficient to drive the particular type and size ofnail. The driving force is all the more effective because the controlvalve 56 is opened by the air pressure in the lower chamber 6%). Thisopening movement is more rapid and consistent from operation tooperation than could be provided by any manual movement. In this way aminimum back pressure must be overcome in propelling the driver pistonit should be noted that air cannot pass outwardly through the packing 88so that all of the energy of the air in the lower chamber 60 iseffective in opening the valve 56.

The relative position of the spool valve 106 within the two diameterbore 8%) places the passageways 73 and 142 in direct communicaiton andthe signal line 30 is pressurized at full line pressure therebyproviding effective means for actuating the control valve 36 which inturn initiates the cycle for delivering a further nail to the quill assoon as the gun is removed from the workpiece.

As seen in Fig. 2 the pressure in the signal line 30 moves the piston163 to the left, the line 165 being thus pressurized and lines 162 and165' being vented to atmosphere. The reversal of forces on the piston161 causes it to move to the left actuating the lift slide 154 todeliver nails to the raceway 156, and moving the separating segment 158to a fastener receiving position adjacent the raceway. The pressure inthe line 165 displaces the piston 164' of the time delay valve 164 tothe right removing the restriction in the line 162 but since the line162 is vented to atmosphere through the valve 36 no pressurized airflows to the delivery tube 28 at this time.

When the gun 213 is removed from the workpiece the pilot valve Hi6 andthe two diameter bore assume their original positions relative to eachother due to the pressure in the line 26 exerting a greater force on thelarger diameter lower spool of the valve 106 than on the smaller.Pressurized air again flows to the lower side of the control valve 56through the annular chamber 84 and the holes 86. The control valvequickly seals off the lower chamber 64 and air passes between thepacking 88 and the driver 46 to bring the lower chamber back to fullline pressure. As the pressure in the lower chamber increases the driverpiston 44 is displaced upwardly toward its inactive position,recompressing the air in the upper chamber 62 and in the accumulator 64to the desired pressure. The initial upward movement of the piston 44 isquite rapid but is effectively slowed down as the pressure in the upperchamber increases; thus there is no shock when the piston 44 reaches theend of its return stroke. Usually the driver piston does not return toits uppermost position until the pressure in the upper chamber 62 isreduced a slight amount at which time the piston 44 will be displacedupwardly to an extent sufficient to open the pressure regulating valve96 against the action of the spring 98 allowing further air to enter theupper chamber 62 and the accumulator 64 increasing the pressure to thedesired value whereupon the piston will be moved away from the valve 96and the valve will again close.

With the removal of the gun from the workpiece and the return of thepilot valve 106 to its lower position relative to the two diameter bore80, the pressurized air in the signal line 30 is vented to atmospherethrough the passageway 142 and a passageway 143 in the middle of thevalve 106. The depressurization of the line 38 permits the piston 163 toreturn to its right-hand position thus causing lines and 162. again tobecome pressurized and line 165 to be vented to atmosphere to return thepiston 161 to its right-hand position. Thereupon the lift slide 154moves downwardly and the separating segment 158 moves to deliver theendmost nail to the raceway in alinement with the, delivery tube 28.Although the line 165, is now vented, the piston 164 of the time delayvalve 164 does not return toits left-hand position until a blast of airpasses through line 162 to blow the nail through the delivery tube 128to the gun. The cycle of operation having been completed the gun is nowready to insert another nail.

When the supply line 26 is disconnected after operation of the gun 20,the air compressed within the upper chamber 62 andthe accumulator 64cannot vent through the valve 96. It is necessary that the gun 20 not befired except when pressed against a workpiece to bring the quill lockingsleeve 130 out of locking relationship with respect to the quill 114.Therefore, the ball check 82 (Fig. is provided to prevent the controlvalve 56 from being actuated when the pressure in the supply line 26 iscut off. Pressure is thus held in the chamber 60 until leakage by theball check 82 relieves it. When the line 26 is vented pressure on top ofthe valve 96 is relieved. The pressure in chamber 62 forces the valve 96open allowing the piston to move upward due to thelocked-in pressure inthe chamber 60 which fully opens the valve 96 and fully vents thechamber 62. Chamber 60 now slowly leaks pressure by ball check 82 untilat atmospheric pressure. Thus it is always insured that the driver endsup in the inactive position when the line 26 is depressurized and thedriver cannot move downward to destroy the locked quill.

It will be noted that there are only two springs in the present gun,namely, the pressure regulating valve spring 98 and the spring 140 inthe nose piece 24. Furthermore, these springs in no way affect controlof the actual operation of the air motor which provides the drivingforce for the inserting gun. The spring 98 is of course of greatimportance in controlling the pressure differential between the upperchamber 62 and the lower chamber 60 but does not actually controloperation of the driver piston 44. This feature wherein fluid forcedifferentials are utilized to displace the driver piston 44, the controlvalve 56 and the pilot valve 106 makes for a very simple and highlyeffective construction. It should be noted that with the aboveadvantages in mind, it is further possible to return the driver piston44 to its ready position without venting the upper chamber 62 toatmosphere and yet employ a single diameter driving piston. This leadsto a great economy in air consumption in the operation of the presentdevice as well as simplicity and reliability of operation. Furthermore,the provision of an accumulator surrounding the cylinder 42 of the airmotor serves an added purpose in allowing extremely light weightconstruction since the cylinder 42 is effectively protected from damageby abuse in the normal use of this inserting gun.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

l. A fluid motor comprising a cylinder, a piston slidable therein andseparating said cylinder into first and sec ond chambers on either sidethereof, a single line for delivering compressed fluid to said fluidmotor, means for introducing fluid under pressure from said line intosaid first chamber whereby a force will be exerted on said piston todisplace it to an inactive position, a passageway leading from said lineto said second chamber, means interposed in said passageway foradmitting a limited supply of fluid under pressure to said secondchamber when said piston is in the inactive position to maintain in saidsecond chamber a pressure less than the pressure in said first chamber,and means for releasing the pressurized fluid from said first chamber toallow the fluid in said second chamber to expand and thereby drive saidpiston away from said inactive position and toward a force deliveringposition.

2. A fluid motor comprising a cylinder, a piston slidable therein andseparating said cylinder into first and second chambers on either sidethereof, valve means for introducing and maintaining fluid underpressure in said first chamber to maintain said piston in an inactiveposition, means for maintaining in said second chamber compressed fluidwhich is at a pressurev below the pressure in said first chamber whensaidvpiston is in said inactive position, means for displacing saidvalve means to release the pressurized fluid from said first chamber toallow the fluid in said second chamber to expand and thereby drive saidpiston away from said inactive position and to a. force deliveringposition, and means for varying the pressure in said second chamberwhereby the energy with which said piston is driven to its forcedeliveringposition may be controlled.

3. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston and beyond saidcylinder, valve means for introducing and maintaining fluid underpressure in said first chamber to maintain said piston in an inactiveposition, means formaintaining in said second chamber compressedfluidwhich is at a pressure below the pressure in said first chamberwhen said piston is in said inactive position, and means for displacingsaid valve means to release the pressurized fluid from said firstchamber to allow the fluid in said second chamber to expand and therebymove said piston and driver away from said inactive position and to aforce delivering position.

4. A fastener inserting gun comprising a cylinder, a

piston slidable therein and separating said cylinder into first andsecond chambers on either side thereof, an accumulator for containingcompressed fluid which is in direct communication with saidsecondchamber, a driver extending from said piston and beyond said cylinder,valve means for introducing and maintaining fluid under pressure in saidfirst chamber to maintain said piston inan inactive position, means f ormaintaining in said second chamber and in said accumulator compressedfluid which is at a pressure below the pressure in said first chamberwhen said piston is in said inactive position, and means for displacingsaid valve means to release the pressurized fluid from said firstchamber to allow the fluid in said second chamber and in saidaccumulator to expand and thereby drive said piston and driver away fromsaid inactive position and to a force delivering position. 5. A fastenerinserting gun comprising a cylinder, a piston slidable therein andseparating said. cylinder into first and second chambers on either sidethereof, a driver extending from saidpiston andv beyond said cylinder,at single line for delivering compressed fluid tosaid insert ing gun,means for introducing fluid under pressure from said line into saidfirst chamber whereby a force will be exerted on said piston to displaceit to an inactive position, a passageway leading from said line to saidsecond chamber, means interposed in said passageway for adinitting alimited supply of fluid under pressure to said second chamber when saidpiston is in the inactive position to maintain in said second chamber apressure less than the pressure in said first chamber, and means forreleasing the pressurized fluid from said first chamber to allow thefluid in said second chamber to expand and thereby drive said piston anddriver away from said inactive position and to aforce deliveringposition.

.6. A f astener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said pistonv and.beyondisaid cylinder, a single line for delivering compressed fluid tosaid inserting gun, means for introducing fluid under pressure from saidline into said first chamber whereby a force will be 'exertedon saidpiston to displace it to an inactive position, a passageway leading fromsaidline tosaid second chamber, a valve interposed in said passagewayfor controllingthe admission of fluid tosaid second chamber,

11 yieldable pressure means normally holding said valve closed, meansresponsive to movement of said piston toward said inactive position foropening said valve whereby pressurized fluid is introduced into saidsecond chamber until the pressure in said second chamber, in combinationwith the yieldable pressure means, displaces said piston to a pointwheresaid valve is closed thereby introducing fluid into said second chamberwhich is at a pressure less than the pressure in said first chamber, andmeans for releasing the pressurized fluid from said first chamber toallow the fluid in said second chamber to expand and thereby drive saidpiston and driver away from said inactive position and to a forcedelivering position.

7. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston and beyond saidcylinder, a single line for delivering compressed fluid to saidinserting gun, means for introducing fluid from said line into 'saidfirst chamber whereby a force will be exerted on said piston to displaceit to an inactive position, an accumulator for containing pressurizedfluid which is in direct communication with said second chamber, apassageway leading from said line to said chamber and accumulator, meansinterposed in said passageway for admitting a limited supply of fluidunder pressure to said second chamher when said piston is in theinactive position to maintain in said second chamber a pressure lessthan the in said first chamber, and means for releasing the pressurizedfluid from said first chamber to allow the fluid in said second chamberand in said accumulator to expand and thereby drive said piston anddriver away from said inactive position and to a force deliveringposition. t

8. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first andsecond chambers oneither side thereof, a driver extendingfrom said piston and beyond saidcylinder, valve means for introducing and maintaining fluid underpressure in said first chamber to maintain said piston in an inactiveposition, an accumulator which is formed by a concentric casingsurrounding said cylinder through its entire length and which is indirect communication with said second chamber, means for introducingcompressed fluid into said second chamber and accumulator,

and means for releasing said valve means whereby said piston and driverare driven from said inactive position to a force delivering position bythe fluid compressed in said accumulator and said second chamber.

9. A fluid motor comprising a cylinder, a piston slidable therein andseparating said cylinder into first and second chambers on either sidethereof, a plurality of passageways for venting said first chamber, avalve member movable in a direction axially of said cylinder foralternatively sealing off said first chamber from and exposing it tosaid passageways, means for introducing fluid under pressure against theface of said valve member remote from said first chamber to maintainsaid valve member: in sealing position, said valve member having meanspermitting the passage of fluid therethrough to said first chamberwhereby fluid under pressure enters said first chamber to displace saidpiston to an inactive position, means within said second chamber forexerting at all times a force against said piston which tends to urgesaid piston away from said inactive position and to a force ton to bedriven toward said force delivering position by the force within saidsecond chamber.

I O A fastener inserting gun comprising a cylinder,

a piston slidable therein and separating said cylinder into first andsecond chambers on either side thereof, a driver extending from saidpiston through said first chamber and beyond said cylinder, a pluralityof passageways for venting said first chamber, a valve member movable ina direction axially of said cylinder for alternatively sealing off saidfirst chamber from and exposing it to said passageways, means forintroducing fluid under pressure against the face of said valve memberremote from said first chamber to maintain said valve member in itssealing position, said valve member having means permitting the passageof fluid theret'hrough to said first chamber, whereby fluid underpressure enters said first chamber to displace said piston to aninactive position, said introducing means including a pilot valve whichin one position permits passage of fluid to said valve member and in asecond position releases the fluid pressure acting against said valvemember, means within said second chamber for exerting at all times aforce against said piston which tends to urge said piston away from saidinactive position and to a force delivering position, and means formoving said pilot valve to its second position whereby fluid pressureacting against said valve member is released and said member isdisplaced from its sealing position by the fluid pressure in said firstchamber and said fluid is vented through said passageways to allow saidpiston to be driven toward said force delivering position by the forcewithin said second chamber.

11. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston through saidfirst chamber and beyond said cylinder, an accuculator for containingcompressed fluid which is in direct communication with said secondchamber, a plurality of passageways for venting said first chamber, avalve member movable in a direction axially of said cylinder foralternatively sealing off said first chamber from and exposing it tosaid passageways, means for introducing fluid under pressure against theface of said valve member remote from said first chamber to maintainsaid valve member in its sealing position, said valve member havingmeans permitting the passage of fluid therethrough to said first chamberWhereby fluid under pressure enters said first chamber to displace saiddriver piston to an inactive position, means for maintaining in saidsecond chamber and in said accumulator compressed fluid which is at apressure below the pressure in said first chamber when said driverpiston is in its inactive position, and means for releasing the fluidpressure acting against said valve member whereby said member isdisplaced from its sealing position by the fluid pressure in said firstchamber and said fluid is vented through said passageways to allow thefluid in said second chamber and in said accumulator to expand andthereby drive said piston and driver away from said inactive positionand to a force delivering position.

12. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston and beyond saidcylinder, a single line for delivering compressed fluid to saidinserting gun, a plurality of passageways for venting said firstchamber, a valve member movable in a direction axially of said cylinderfor alternatively sealing ofl. said first chamber from and exposing itto said passageways, means for introducing fluid under pressure fromsaid line against the face of said valve member remote from said firstchamber to maintain said valve member in its sealing position, saidvalve member having means permitting the passage of fluid therethroughto said first chamber, whereby fluid under pressure enters said firstchamber to dis place said driver piston to an inactive position, apassageway leading from said line to said second chamber, meansinterposed in said passageway for admitting a limited supply of fluidunder pressure to said second chamber when said piston is in theinactive position to maintain in said second chamber a pressure lessthan the pressure in said first chamber, and means for releasing thefluid pressure acting against said valve member whereby said valvemember is displaced from its sealing position by the fluid pressure insaid first chamber, and said fluid is vented through said passageways toallow the fluid in said second chamber to expand and thereby drive saidpiston and driver away from said inactive position and to a forcedelivering position.

13. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston and beyond saidcylinder, a single line for delivering compressed fluid to saidinserting gun, a plurality of passageways for venting said firstchamber, a valve member for sealing off said first chamber from saidpassageways, said valve member having means permitting the passage offluid therethrough to said first chamber, means for introducing fluidunder pressure from said line against the outer face of said valvemember whereby it is maintained in its sealing position and fluid enterssaid first chamber to maintain said driver piston in an inactiveposition, a passageway leading from said line to said second chamber,means interposed in said passageway for admitting a limited supply offluid to said second chamber whereby the pressure in said second chamberis less than the pressure in said first chamber when the piston is insaid inactive position, means for releasing the fluid pressure actingagainst said valve member whereby said member is displaced from itssealing position by the fluid pressure in said first chamber and saidfluid is vented through said passageways to allow said piston and driverto be driven to a force delivering position by the expansion of thefluid within said second chamber, and means for preventing the releaseof the fluid pressure acting against said valve member when the pressurein said delivery line is shut off whereby said inserting gun may bedisengaged from a source of pressurized fluid with its driver piston inits inactive position.

14. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston and beyond saidcylinder, valve means for introducing and maintaining fluid underpressure in said first chamber to maintain said piston in an inactiveposition, means for maintaining in said second chamber compressed fluidwhich is at a pressure below the pressure in said first chamber whensaid driver piston is in said inactive position, means for displacingsaid valve means to release the pressurized fluid from said firstchamber to allow the fluid in said second chamber to expand and therebydrive said piston and driver away from said inactive position and to aforce delivering position, and means for varying the pressure in saidsecond chamber whereby the energy imparted to said piston and driver maybe matched to the energy necessary for driving a fastener.

15. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston and beyond saidcylinder, a single line for delivering compressed fluid to saidinserting gun, means for introducing fluid from said line into saidfirst chamber whereby said chamber is at line pressure and said pistonis maintained in an inactive position, a passageway leading from saidline to said second chamber, a valve interposed in said line forcontrolling the admission of fluid to said second chamber, yieldablemeans normally holding said valve closed, means responsive to movementof said piston for opening said valve whereby pressurized fluid isintroduced into said second chamber until the pressure in said secondchamber in combination with the yieldable means displaces said piston toa point where said valve is closed thereby introducing fluid into saidsecond chamber which is. at a pressure less than the pressure in saidfirst chamber when the driver piston is in its inactive position, meansfor varying the force of said yieldable means whereby the pressure ofthe fluid in said second chamber may be varied, and means for releasingthe pressurized fluid from said first chamber to allow the fluid in saidsecond chamber to expand and thereby drive said piston and driver awayfrom said inactive position and to a force delivering position.

16. A fastener inserting gun comprising a cylinder, a driver pistonslidable therein and separating said cylinder into first and secondchambers on either side thereof, a plurality of passageways for ventingsaid first chamber, a valve member sealing off said first chamber fromsaid passageways, said valve member having means permitting the passageof fluid therethrough to said first chamber, means for introducing fluidunder pressure against the outer face of said valve member whereby it ismaintained in its sealing position and fluid enters said firstchamber tomaintain the driver piston in an inactive position, said introducingmeans including a pilot valve which is movable between a first positionin which fluid is introduced against the outer face of said valve memberand a second position in'which the fluid acting against said valvemember is released, a fluid conduit extending from said gun at a pointadjacent said pilot valve whereby when said pilot valve is in its secondposition the conduit is pressurized to initiate the delivery of afastener to the gun, means within said second chamber for exerting atall times a force against said piston which tends to urge said driverpiston away from said inactive position and to a. force deliveringposition, and means for moving said pilot valve to its second positionwhereby the fluid acting against said valve member is released and saidmember is displaced from its sealing position by the fluid pressure insaid first chamber and said fluid is vented through said passageways toallow said driver piston to be driven toward said force deliveringposition by the force within said second chamber.

17. A fluid motor comprising a cylinder, a piston slidable therein andseparating said cylinder in-to first and second chambers on either sidethereof, a plurality of passageways for venting said first chamber, avalve member for sealing off said cylinder from said passageways, saidvalve member having means permitting the passage of fluid therethroughto said first chamber, means for introducing fluid under pressureagainst the outer face of said valve member whereby it is maintained inits sealing position and fluid enters said first chamber to maintainsaid piston in an inactive position, means within said second chamberfor exerting at all times a force against said piston which tends tourge said piston away from said inactive position and toward a forcedelivering position, said introducing means including a pilot valvehaving two spools with opposed surfaces one of which is larger in areathan the other, said pilot valve being movable in a closed chamber,means for introducing fluid between said spools whereby said pilot valveis maintained in a first position in which fluid is introduced againstthe outer face of said valve, and means for shifting said pilot valve toa second position in which the fluid pressure acting against said valvemember is released and said member is displaced from its sealingposition by the fluid pressure in said first chamber and said fluid isvented through said passageways to allow said piston to be driven to itsforce delivering position by the force in said second chamber.

18. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston and beyond saidcylinder, a plurality of passageways for venting said first chamber, avalve member for sealing off said first chamber from said passageways,said valve member having means permitting the passage of fluidtherethrough to said first chamber, means for introducing fluid pressureagainst the outer face of said valve member whereby it is maintained inits sealing position and fluid enters said first chamber to maintainsaid driver piston in an inactive position, said introducing meansincluding a pilot valve which in a first postion permits passage offluid to said valve member and in a second position releases the fluidpressure acting against said valve member, means within said secondchamber for exerting at all times a force against said driver pistonwhich tends to urge said piston away from said inactive position andtoward a force delivering position, means for normally maintaining saidpilot valve in its first position, and means extending from said gunwhich upon engagement with a workpiece will displace said pilot valve toits second position whereby fluid pressure acting against said valvemember is released and said member is displaced from its sealingposition by the fluid pressure in said first chamber, and said fluid isvented through said passageways to allow said piston and driver tosbedriven toward said force delivering position by the force .within saidsecond chamber.

l9. A fastener inserting gun comprising a fluid motor having a driverpiston and a driver extending therefrom, means 'for locating a fastenerin alinement with said driver, said locating means being yieldablymounted at one end of saidgun, a conduit leading to said locating meansthrough which fasteners may be delivered a control valve for actuatingsaid motor, a pilot valve movable relative to said fluid motor which maybe displaced to actuate said control valve, means connecting saidlocating means and said pilot valve whereby when said locating means arepressed against a workpiece relative movement takes place between saidfluid motor and said pilot valve to actuate said fluid motor and therebycause a fastener located in alinement with said driver to be driven.

20. A fastener inserting gun comprising a fluid motor having a driverpiston and a driver extending therefrom, means for locating a fastenerin alinement with said driver, said locating means being slidablymounted at one end of said gun, a pilot valve movable relative to saidfluid motor for controlling fluid flow thereto, a conduit leading tosaid locating means through which fasteners may be delivered, means forretaining a fastener within said locating means, and means connectingsaid locating means and said pilot valve whereby when said locatingmeans are pressed against a workpiece relative movement takes placebetween said fluid motor and said pilot valve to actuate said fluidmotor and said locating means are also displaced with respect to saidretaining means thereby permitting fasteners to be driven from saidlocating means by said driver.

' 21. A fastener inserting gun comprising a fluid motor having acylinder, a driver piston and a driver extending therefrom, means forlocating a fastener in alinement with said driver, a pilot valve movablerelative to said fluid motor for controlling fluid flow to said motor, aconduit leading to said locating means through which fasteners may bedelivered, means for retaining a fastener within said locating meanscomprising a sleeve surrounding said locating means yieldably mountedwith respect to said fluid motor, said locating means beinglongitudinally movable with respect to said cylinder, and meansconnecting said locating means and said pilot valve whereby when saidlocating means are pressed against a workpiece relative movement takesplace between said fluid motor and said pilot valve to actuate saidfluid motor and said locating means are displaced with respect to saidretaining means, and upon release from said workpiece the locating meansmay return to their normal position before the retaining means.

22. A fastener inserting gun comprising a cylinder, a piston slidabletherein and separating said cylinder into first and second chambers oneither side thereof, a driver extending from said piston and beyond saidcylinder, a single line for delivering compressed fluid to saidinserting gun, a plurality of passageways for venting said firstchamber, a valve member for sealing off said passageways, said valvemember having means permitting the passage of fluid therethrough to saidfirst chamber, means for introducing fluid under pressure from said lineagainst the outer face of said valve member whereby it is maintained inits sealing position and fluid enters said first chamber to maintainsaid driver piston in an inactive position, a passageway leading fromsaid line to said second chamber, means interposed in said passagewayfor admitting a limited supply of fluid to said second chamber wherebythe pressure in said second chamber is less than the pressure in saidfirst chamber when the piston is in said inactive position, means forlocating a fastener in alinement with said driver, said locating meansbeing slidably mounted at one end of said gun, means operative inresponse to movement of said locating means with respect to saidcylinder for releasing said fluid pressure against said valve member,and means for preventing the release of the fluid pressure actingagainst said valve memher when the pressure in said delivery line isshut off, whereby said inserting gun may bedisengaged from a source ofpressurized fluid with the driver piston remaining in an inactiveposition.

References Cited in the file of this patent UNITED STATES PATENTS1,014,639 Colwell Jan. 16, 1912 2,498,503 Papalia Feb. 21, 19502,625,682 Cristiano Jan. 20, 1953 2,679,826 Leavell June 1, 19542,707,277 Aldrich May 3, 1955

